To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera, Delphacidae), has emerged as a serious rice pest in Asia. In the present study, 12 microsatellite markers were employed to investigate the genetic structure, diversity and migration route of 43 populations sampled from seven Asian countries (Bangladesh, China, Korea, Laos, Nepal, Thailand, and Vietnam). According to the isolation by distance analysis, a significant positive correlation was observed between genetic and geographic distances by the Mantel test (r2 = 0.4585, P = 0.01), indicating the role of geographic isolation in the genetic structure of S. furcifera. A population assignment test using the first-generation migrants detection method (thresholds a = 0.01) revealed southern China and northern Vietnam as the main sources of S. furcifera in Korea. Nepal and Bangladesh might be additional potential sources via interconnection with Vietnam populations. This paper provides useful data for the migration route and origin of S. furcifera in Korea and will contribute to planthopper resistance management.
This study aimed to identify the effect of lateral neck dissection on voice change in thyroidectomised patients.
Medical records from 264 patients who underwent thyroidectomy with (n = 65) or without (n = 199) lateral neck dissection were reviewed. Clinical and voice evaluation data were compared between the two groups.
Patients who underwent surgery that included lateral neck dissection had lower fundamental frequencies and speaking fundamental frequencies. They also had a higher incidence of asymmetric mucosal wave and vocal fold oedema on videostroboscopy during the first month after surgery, with the incidence of vocal fold oedema remaining significantly higher at three months. Self-assessed voice quality scores were significantly higher in lateral neck dissection patients at both one and three months after surgery.
In thyroidectomised patients, lateral neck dissection lowers the vocal pitch in the initial period after surgery and induces vocal fold oedema that persists for several months. Although most objective parameters improved within a month, subjective symptoms lasted for longer.
A new approach is proposed to analyze Bremsstrahlung X-rays that are emitted from laser-produced plasmas (LPP) and are measured by a stack type spectrometer. This new method is based on a spectral tomographic reconstruction concept with the variational principle for optimization, without referring to the electron energy distribution of a plasma. This approach is applied to the analysis of some experimental data obtained at a few major laser facilities to demonstrate the applicability of the method. Slope temperatures of X-rays from LPP are determined with a two-temperature model, showing different spectral characteristics of X-rays depending on laser properties used in the experiments.
The Ultra-Fast Flash Observatory (UFFO), which will be launched onboard the
Lomonosov spacecraft, contains two crucial instruments: UFFO Burst
Alert & Trigger Telescope (UBAT) for detection and localization of Gamma-Ray Bursts
(GRBs) and the fast-response Slewing Mirror Telescope (SMT) designed for the observation
of the prompt optical/UV counterparts. Here we discuss the in-space calibrations of the
UBAT detector and SMT telescope. After the launch, the observations of the standard X-ray
sources such as pulsar in Crab nebula will provide data for necessary calibrations of
UBAT. Several standard stars will be used for the photometric calibration of SMT. The
celestial X-ray sources, e.g. X-ray binaries with bright optical sources
in their close angular vicinity will serve for the cross-calibration of UBAT and SMT.
The Ultra-Fast Flash Observatory (UFFO) Pathfinder for Gamma-Ray Bursts (GRBs) consists
of two telescopes. The UFFO Burst Alert & Trigger Telescope (UBAT) handles the
detection and localization of GRBs, and the Slewing Mirror Telescope (SMT) conducts the
measurement of the UV/optical afterglow. UBAT is equipped with an X-ray detector, analog
and digital signal readout electronics that detects X-rays from GRBs and determines the
location. SMT is equipped with a stepping motor and the associated electronics to rotate
the slewing mirror targeting the GRBs identified by UBAT. First the slewing mirror points
to a GRB, then SMT obtains the optical image of the GRB using the intensified CCD and its
readout electronics. The UFFO Data Acquisition system (UDAQ) is responsible for the
overall function and operation of the observatory and the communication with the satellite
main processor. In this paper we present the design and implementation of the electronics
of UBAT and SMT as well as the architecture and implementation of UDAQ.
One of the unexplored domains in the study of gamma-ray bursts (GRBs) is the early time
phase of the optical light curve. We have proposed Ultra-Fast Flash Observatory (UFFO) to
address this question through extraordinary opportunities presented by a series of small
space missions. The UFFO is equipped with a fast-response Slewing Mirror Telescope that
uses a rapidly moving mirror or mirror array to redirect the optical beam rather than
slewing the entire spacecraft or telescope to aim the optical instrument at the GRB
position. The UFFO will probe the early optical rise of GRBs with sub-second response, for
the first time, opening a completely new frontier in GRB and transient studies. Its fast
response measurements of the optical emission of dozens of GRB each year will provide
unique probes of the burst mechanism and test the prospect of GRB as a new standard
candle, potentially opening up the z > 10 universe. We describe the current limit in
early photon measurements, the aspects of early photon physics, our soon-to-be-launched
UFFO-pathfinder mission, and our next planned mission, the UFFO-100.
The Slewing Mirror Telescope (SMT) is the UV/optical telescope of UFFO-pathfinder. The
SMT optical system is a Ritchey-Chrétien (RC) telescope of 100 mm diameter pointed by
means of a gimbal-mounted flat mirror in front of the telescope. The RC telescope has a
17 × 17arcmin2 in Field of View and 4.3 arcsec resolution (full width half
maximum of the point spread function) The beam-steering mirror enables the SMT to access a
35 × 35degree region and point and settle within 1 sec. All mirrors were fabricated to
about 0.02 wavelengths RMS in wave front error (WFE) and 84.7% average reflectivity over
200 nm ~ 650 nm. The RC telescope was aligned to 0.05 wavelengths RMS in WFE (test
wavelength 632.8 nm). In this paper, the technical details of the RC telescope and slewing
mirror system assembly, integration, and testing are given shortly, and performance tests
of the full SMT optical system are reported.
The UFFO (Ultra-Fast Flash Observatory) is a GRB detector on board the Lomonosov
satellite, to be launched in 2013. The GRB trigger is provided by an X-ray detector,
called UBAT (UFFO Burst Alarm & Trigger Telescope), which detects X-rays from the GRB
and then triggers to determine the direction of the GRB and then alerts the Slewing Mirror
Telescope (SMT) to turn in the direction of the GRB and record the optical photon fluxes.
This report details the calibration of the two components: the MAPMTs and the YSO crystals
and simulations of the UBAT. The results shows that this design can observe a GRB within a
field of view of ±35° and can trigger in a time scale as short as 0.2 – 1.0 s
after the appearance of a GRB X-ray spike.
The Ultra-Fast Flash Observatory (UFFO) is a space observatory for optical follow-ups of
gamma ray bursts (GRBs), aiming to explore the first 60 seconds of GRBs optical emission.
UFFO is utilized to catch early optical emissions from GRBs within few sec after trigger
using a Gimbal mirror which redirects the optical path rather than slewing entire
spacecraft. We have developed a 15 cm two-axis Gimbal mirror stage for the UFFO-Pathfinder
which is going to be on board the Lomonosov satellite which is to be launched in 2013. The
stage is designed for fast and accurate motion with given budgets of 3 kg of mass and 3
Watt of power. By employing stepping motors, the slewing mirror can rotate faster than 15
deg/sec so that objects in the UFFO coverage (60 deg × 60 deg) can be targeted in
~1 sec. The obtained targeting resolution is better 2 arcmin using a close-loop
control with high precision rotary encoder. In this presentation, we will discuss details
of design, manufacturing, space qualification tests, as well as performance tests.
The Ultra-Fast Flash Observatory (UFFO) aims to detect the earliest moment of Gamma-Ray
Bursts (GRBs) which is not well known, resulting into the enhancement of GRB mechanism
understanding. The pathfinder mission was proposed to be a scaled-down version of UFFO,
and only contains the UFFO Burst Alert & Trigger Telescope (UBAT) measuring the
X-ray/gamma-ray with the wide-field of view and the Slewing Mirror Telescope (SMT) with a
rapid-response for the UV/optical photons. Once the UBAT detects a GRB candidate with the
position accuracy of 10 arcmin, the SMT steers the UV/optical photons from the candidate
to the telescope by the fast rotatable mirror and provides the early UV/optical photons
measurements with 4 arcsec accuracy. The SMT has a modified Ritchey-Chrètien telescope
with the aperture size of 10 cm diameter including the rotatable mirror and the image
readout by the intensified charge-coupled device. There is a key board called the UFFO
Data Acquisition system (UDAQ) that manages the communication of each telescope and also
of the satellite and the UFFO overall operation. This pathfinder is designed and built
within the limited size and weight of ~20 kg and the low power consumption up to
~30 W. We will discuss the design and performance of the UFFO-pathfinder, and its
integration to the Lomonosov satellite.
One of the key aspects of the upcoming Ultra-Fast Flash Observatory (UFFO) pathfinder for
Gamma Ray Bursts (GRBs) identification is the UFFO Burst Alert & Trigger Telescope
(UBAT). The scientific propose of UBAT is to detect and locate as fast as possible the
GRBs in the sky. This is achieved by using a coded mask aperture camera scheme with a wide
field of view (FOV) and selecting a X-ray detector of high quantum efficiency and large
detection area. This X-ray detector of high quantum efficiency and large detection area is
called the UBAT detector. The UBAT detector consists of 48 × 48 Yttrium Oxyorthosilicate
(YSO) scintillator crystal arrays and Multi Anode Photomultiplier Tubes (MAPMTs), analog
electronics equipped with ASIC chips, digital electronics equipped with Field Programmable
Gate Array (FPGA) chips, and a mechanical structure that supports all components of the
UBAT detector. The total number of the pixels in the UBAT detector is 2304, and the total
effective detection area is 191 cm2. We will present the design and
construction, and performance of the UBAT detector including the responses of the UBAT
detector to X-ray sources.
The Ultra-Fast Flash Observatory (UFFO) is a space mission to detect the early moments of an explosion from Gamma-ray bursts (GRBs), thus enhancing our understanding of the GRB mechanism. It consists of the UFFO Burst & Trigger telescope (UBAT) for the recognition of GRB positions using hard X-ray from GRBs. It also contains the Slewing Mirror Telescope (SMT) for the fast detection of UV-optical photons from GRBs. It is designed to begin the UV-optical observations in less than a few seconds after the trigger. The UBAT is based on a coded-mask X-ray camera with a wide field of view (FOV) and is composed of the coded mask, a hopper and a detector module. The SMT has a fast rotatable mirror which allows a fast UV-optical detection after the trigger. The telescope is a modified Ritchey-Chrétien telescope with the aperture size of 10 cm diameter, and an image intensifier readout by CCD. The UFFO pathfinder is scheduled to launch into orbit on 2012 June by the Lomonosov spacecraft. It is a scaled-down version of UFFO in order to make the first systematic study of early UV/optical light curves, including the rise phase of GRBs. We expect UBAT to trigger ~44 GRBs/yr and expect SMT to detect ~10 GRBs/yr.
To determine the relative quantities of two hepatotoxic pyrrolizidine alkaloids, symphytine and echimidine, in teas prepared from comfrey leaves (Symphytum officinale), and to determine the potential contribution of the N-oxide forms of these alkaloids to levels of the parent alkaloids.
Comfrey leaves were purchased from three commercial sources and used to prepare tea in a manner consistent with the methods used by consumers. An extraction scheme was devised for extraction of the alkaloids, and a gas chromatographic method was developed to quantify the two major alkaloids, symphytine and echimidine. Recognising that the N-oxide derivatives of these alkaloids have also been identified in comfrey preparations, chemical reduction was applied to determine the total quantities of the alkaloids as free bases and as N-oxide derivatives.
The concentration of symphytine and echimidine varied considerably between teas prepared from leaves purchased from the different vendors of plant material. Moreover, a much higher concentration of symphytine was found in the tea when steps were included to reduce N-oxides prior to analysis. The treatment of pure symphytine with hot water did not generate the N-oxide derivative de novo.
Since the pyrrolizidine alkaloids are known to be hepatotoxic, consumption of herbal teas made from comfrey leaves may be ill-advised. The concentration of pyrrolizidine alkaloids in such teas may be underestimated substantially unless the concentration of N-oxides is taken into consideration.
InGaN/GaN multi-quantum well (MQW) laser diodes (LDs) were grown on c-plane sapphire substrates using a multi-wafer MOCVD system. The threshold current for pulsed lasing was 1.6 A for a gain-guided laser diode with a stripe of 10 × 800 μm2. The threshold current density was 20.3 kA cm−2 and the threshold voltage was 16.5 V. The optical power ratio of transverse electric mode to transverse magnetic mode was found to be greater than 50. The characteristic temperature measured from the plot of threshold current versus measurement temperature was between 130 and 150K.
High quality ZnS epilayers were grown on GaAs and GaP substrates by hot wall epitaxy. The optimum temperature conditions for high quality ZnS epilayer were found. The photoluminescence(PL) spectrum of high quality ZnS epilayers showed sharp and narrow exciton peaks and no self-activated peaks. The room temperature energy gap of ZnS/GaAs was found to be 3.729 eV from the experimentally observed free exciton PL peaks. The temperature dependence of the PL intensity showed a two step quenching process and the temperature dependence of the PL linewidth broadening was tried to analyze in terms of exciton scattering process. From the splitting of the heavy hole and the light hole exciton peaks, the strain was identified.
Rapid thermal annealing (RTA) was applied to anneal polycrystalline CdTe thin films evaporated on CdS/ITO substrate and the effects of rapid thermal annealing temperatures and gas environments were studied. X-ray diffractometer (XRD), X-ray photoelectron spectroscopy(XPS), energy dispersive X-ray spectroscopy(EDX), cross-sectional transmission microscopy(TEM), and micro-EDX in TEM were used to characterize physical and chemical properties of rapid thermal annealed CdTe thin films. Complete CdTe/CdS photovoltaic cells were fabricated and I-V characteristics of these cells were measured under the illumination. Results showed that the bulk composition of CdTe remained stoichiometric to 550°C in the air environment and surface composition became Cd-rich. Cross-sectional TEM and micro-EDX showed columnar grains and micro-twins remained even after RTA, however, sulfur content in rapid thermal annealed CdTe caused by sulfur diffusion from CdS during the annealing was much smaller than that by furnace annealing. Among the investigated RTA temperatures and gas environments, the cell made with CdTe annealed at 550°C in the air showed the best solar energy conversion efficiency.
Polycrystalline samples of HgBa2(Ca0.86Sr0.14)2Cu3O8+δ (denoted as Hg-1223) were prepared by a precursor route, which involves the reaction between HgO and two precursors: Ba2CuO3+x and Ca0.14CuO2. X-ray powder diffraction analysis revealed that the Hg-1223 is isostructural with pristine HgBa2Ca2Cu3O8−δ and TlBa2Ca2Cu3O9−δ. The Hg-1223 has tetragonal symmetry with space group P4/mmm, and lattice parameters a = 3.8648(2) Å and c = 16.0319(2) Å. The as-synthesized Hg-1223 sample has a Tc of about 126 K. After annealing in an oxygen atmosphere at 280 °C for 10 h, the Tc increased to 132 K. Using this precursor pathway, Hg-1223 samples can be reproducibly synthesized.
The GaInP/AlGaInP heterostructure was grown on (100) GaAs substrate using low pressure metal-organic vapor phase epitaxy (LP MOVPE) . The growth temperature and pressure were held constant at 740 °C and 40 torr, respectively. The GalnP multiquantum well layers from 10 Å to 85 A were lattice matched to the substrate. High resolution transmission electron microscopy and low temperature photoluminescence measurements indicated that the GaInP/AlGaInP well layers were uniform in thickness and that the interface was abrupt and free of defects. For high performance of visible laser diodes, highly doped p-AlGaInP layer(8X1017/cm3) was obtained. It was also found that the Zn acceptor concentration increased with growth rate. In this study, the GaInP/AlGaInP laser diode, 645nm and 20mW, was fabricated by employing multiquantum well and highly doped p-cladding layer.
Email your librarian or administrator to recommend adding this to your organisation's collection.